A cross between the self-fertilised
individuals of the same variety does no good whatever to the offspring;
whilst a cross between distinct varieties, though closely allied, does
great good, of which we have excellent evidence. The flowers of the
Broom (Sarothamnus) are almost sterile if they are not disturbed and if
insects are excluded. The pollen from a distinct plant is more effective
than that from the same flower in producing seeds. The crossed seedlings
have an enormous advantage over the self-fertilised when grown together
in close competition. Lastly, only four plants of the Ononis minutissima
were raised; but as these were observed during their whole growth, the
advantage of the crossed over the self-fertilised plants may, I think,
be fully trusted.
[15. ONAGRACEAE.--Clarkia elegans.
Owing to the season being very unfavourable (1867), few of the flowers
which I fertilised formed capsules; twelve crossed flowers produced only
four, and eighteen self-fertilised flowers yielded only one capsule. The
seeds after germinating on sand were planted in three pots, but all the
self-fertilised plants died in one of them. When the two lots were
between 4 and 5 inches in height, the crossed began to show a slight
superiority over the self-fertilised. When in full flower they were
measured, with the following result:--
TABLE 5/62. Clarkia elegans.
Heights of plants measured in inches.
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